Cyanopyrroles

ABSTRACT

This invention provides a progesterone receptor antagonist of formula 1 having the structure 
                         
wherein, T is O, S, or absent; R 1 , and R 2  are each, independently, hydrogen, alkyl, substituted alkyl; or R 1  and R 2  are taken together form a ring and together contain —CH 2 (CH 2 ) n CH 2 —, —CH 2 CH 2 CMe 2 CH 2 CH 2 —, —O(CH 2 ) p CH 2 —, —O(CH 2 ) q O—, —CH 2 CH 2 OCH 2 CH 2 —, or —CH 2 CH 2 NR 7 CH 2 CH 2 —; n=1-5; p=1-4; q=1-4; R 3  is hydrogen, OH, NH 2 , alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, or COR A ; R A  is hydrogen, alkyl, substituted alkyl, alkoxy, substituted alkoxy, aminoalkyl, or substituted aminoalkyl; R 4  is hydrogen, halogen, CN, NH 2 , alkyl, substituted alkyl, alkoxy, substituted alkoxy, aminoalkyl, or substituted aminoalkyl; R 5  is hydrogen, alkyl, or substituted alkyl; R 6  is hydrogen, alkyl, substituted alkyl, or COR B ; R B  is hydrogen, alkyl, substituted alkyl, alkoxy, substituted alkoxy, aminoalkyl, or substituted aminoalkyl; R 7  is hydrogen or alkyl; or a pharmaceutically acceptable salt thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No. 10/342,719, filed Jan. 15, 2003, which is a divisional of U.S. patent application Ser. No. 10/043,513, filed Jan. 9, 2002, now U.S. Pat. No. 6,562,857, which is a divisional of U.S. patent application Ser. No. 09/552,544, filed Apr. 19, 2000, now U.S. Pat. No. 6,407,101, which claims the benefit of the priority of U.S. patent application Ser. No. 60/183,050, filed May 4, 1999, now abandoned.

BACKGROUND OF THE INVENTION

Intracellular receptors (IR) form a class of structurally related gene regulators known as “ligand dependent transcription factors” (R. M. Evans, Science, 240, 889, 1988). The steroid receptor family is a subset of the IR family, including progesterone receptor (PR), estrogen receptor (ER), androgen receptor (AR), glucocorticoid receptor (GR), and mineralocorticoid receptor (MR).

The natural hormone, or ligand, for the PR is the steroid progesterone, but synthetic compounds, such as medroxyprogesterone acetate or levonorgestrel, have been made which also serve as ligands. Once a ligand is present in the fluid surrounding a cell, it passes through the membrane via passive diffusion, and binds to the IR to create a receptor/ligand complex. This complex binds to specific gene promoters present in the cell's DNA. Once bound to the DNA the complex modulates the production of mRNA and protein encoded by that gene.

A compound that binds to an IR and mimics the action of the natural hormone is termed an agonist, whilst a compound that inhibits the effect of the hormone is an antagonist.

PR agonists (natural and synthetic) are known to play an important role in the health of women. PR agonists are used in birth control formulations, typically in the presence of an ER agonist, alternatively they may be used in conjunction with a PR antagonist. ER agonists are used to treat the symptoms of menopause, but have been associated with a proliferative effect on the uterus that can lead to an increased risk of uterine cancers. Co-administration of a PR agonist reduces or ablates that risk.

Jones et al (U.S. Pat. No. 5,688,810) described the PR antagonist dihydroquinoline A.

Jones et al described the enol ether B (U.S. Pat. No. 5,693,646) as a PR ligand.

Jones et al described compound C (U.S. Pat. No. 5,696,127) as a PR ligand.

Zhi et al described lactones D, E and F as PR antagonists (J. Med. Chem. 41, 291, 1998).

Zhi et al described the ether G as a PR antagonist (J. Med. Chem. 41, 291, 1998).

Combs et al disclosed the amide H as a ligand for the PR (J. Med. Chem. 38, 4880, 1995).

Perlman et al described the vitamin D analog I as a PR ligand (Tetrahedron. Lett. 35, 2295, 1994).

Hamann et al described the PR antagonist J (Ann. N.Y. Acad. Sci. 761, 383, 1995).

Chen et al described the PR antagonist K (Chen et al, POI-37, 16^(th) Int. Cong. Het. Chem., Montana, 1997).

Kurihari et al described the PR ligand L (J. Antibiotics 50, 360, 1997).

Kuhla et al claimed the oxindole M as a cardiotonic (WO 86/03749).

Weber claimed the oxindole N for cardiovascular indications (WO 91/06545).

Fischer et al claim a preparation for making compounds which include the generic structure O (U.S. Pat. No. 5,453,516).

Singh et al described the PDE III inhibitor P (J. Med. Chem. 37, 248, 1994).

Andreani et al described the cytotoxic agent Q (Acta. Pharn. Nord. 2, 407, 1990).

Binder et al described structure R which is an intermediate for preparing COX II inhibitors (WO 97/13767).

Walsh (A. H. Robins) described the oxindole S as an intermediate (U.S. Pat. No. 4,440,785, U.S. Pat. No. 4,670,566).

Bohm et al claim the oxindole T as cardiovascular agents (WO 91/06545).

Bohm et al include the generic structure U (WO 91/04974).

A Japanese patent contains the generic structure V (JP 63112584 A).

Boar et al described the dioxolane W as an intermediate for preparation of acetyl-cholinesterase inhibitors (WO 93/12085 A1).

Kende et al described methodology for preparing 3,3-substituted oxindoles, e.g., X, that was utilized in the present invention (Synth. Commun. 12, 1, 1982).

There are numerous literature reports that disclose a number of benzoxazin-2-ones. However, none of these examples in these patents contain substituents necessary for the compounds to be active as progesterone receptor modulators.

Among these publications, Narr et al (German Patent No. DE 3633861, CA 109:22973) discussed imidazobenzoxazinones, e.g. Y, as cardotonics. Benzoxazin-2-ones, such as brofoxine (Z), being active as an anxiolytic was reported by Hartmann et al (Proc. West. Pharmacol. Soc. 21, 51-55 (1978)). More recently, a number of patents (e.g., Young et al WO95/20389; Christ et al. WO98/14436) claimed quinazolin-2-ones and benzoxazin-2-ones such as compounds AA and BB as inhibitors of HIV reverse transcriptase.

DESCRIPTION OF THE INVENTION

This invention provides progesterone receptor agonists of Formula 1 having the structure:

wherein, T is O, S, or absent; R₁, and R₂ are each, independently, hydrogen, alkyl, substituted alkyl; or R₁ and R₂ are taken together form a ring and together contain —CH₂(CH₂)_(n)CH₂—, —CH₂CH₂CMe₂CH₂CH₂—, —O(CH₂)_(p)CH₂—, —O(CH₂)_(q)O—, —CH₂CH₂OCH₂CH₂—, or —CH₂CH₂NR₇CH₂CH₂—; n=1-5; p=1-4; q=1-4; R₃ is hydrogen, OH, NH₂, alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, or COR^(A); R^(A) is hydrogen, alkyl, substituted alkyl, alkoxy, substituted alkoxy, aminoalkyl, or substituted aminoalkyl; R₄ is hydrogen, halogen, CN, NH₂, alkyl, substituted alkyl, alkoxy, substituted alkoxy, aminoalkyl, or substituted aminoalkyl; R₅ is hydrogen, alkyl, or substituted alkyl;

-   R₆ is hydrogen, alkyl, substituted alkyl, or COR^(B); R^(B) is     hydrogen, alkyl, substituted alkyl, alkoxy, substituted alkoxy,     aminoalkyl, or substituted aminoalkyl; -   R₇ is hydrogen or alkyl;

Methods of providing progestational therapy to a mammal in need thereof are provided which include administering a progestationally effective amount of compound formula 1 having the structure:

wherein, T is O, S, or absent; R₁, and R₂ are each, independently, hydrogen, alkyl, substituted alkyl; or R₁ and R₂ are taken together form a ring and together contain —CH₂(CH₂)_(n)CH₂—, —CH₂CH₂CMe₂CH₂CH₂—, —O(CH₂)_(p)CH₂—, —O(CH₂)_(q)O—, —CH₂CH₂OCH₂CH₂—, or —CH₂CH₂NR₇CH₂CH₂—; n=1-5; p=1-4; q=1-4; R₃ is hydrogen, OH, NH₂, alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, or COR^(A); R^(A) is hydrogen, alkyl, substituted alkyl, alkoxy, substituted alkoxy, aminoalkyl, or substituted aminoalkyl; R₄ is hydrogen, halogen, CN, NH₂, alkyl, substituted alkyl, alkoxy, substituted alkoxy, aminoalkyl, or substituted aminoalkyl; R₅ is hydrogen, alkyl, or substituted alkyl; R₆ is hydrogen, alkyl, substituted alkyl, or COR^(B); R^(B) is hydrogen, alkyl, substituted alkyl, alkoxy, substituted alkoxy, aminoalkyl, or substituted aminoalkyl; R₇ is hydrogen or alkyl; or a pharmaceutically acceptable salt thereof, to a mammal. or a pharmaceutically acceptable salt thereof, which are useful for contraception, in the treatment of fibroids, endometriosis, breast, uterine, ovarian and prostate cancer, and post menopausal hormone replacement therapy.

Desired compounds of this invention are those having the structure:

wherein, T is O, or absent; R₁, and R₂ are each, independently, hydrogen, alkyl, substituted alkyl; or R₁ and R₂ are taken together form a ring and together contain —CH₂(CH₂)_(n)CH₂—; n=1-5; R₃ is hydrogen; R4 is hydrogen or halogen; R₅ is hydrogen or alkyl; R₆ is hydrogen or alkyl; or a pharmaceutically acceptable salt thereof.

The compounds of this invention may contain an asymmetric carbon atom and some of the compounds of this invention may contain one or more asymmetric centers and may thus give rise to optical isomers and diastereoisomers. While shown without respect to stereochemistry in Formula 1, the present invention includes such optical isomers and diastereoisomers; as well as the racemic and resolved, enantiomerically pure R and S stereoisomers; as well as other mixtures of the R and S stereoisomers and pharmaceutically acceptable salts thereof.

The compounds of this invention have been shown to act as competitive inhibitors of progesterone binding to the PR and act as agonists in functional models, either/or in-vitro and in-vivo. These compounds may be used for contraception, in the treatment of fibroids, endometriosis, breast, uterine, ovarian and prostate cancer, and post menopausal hormone replacement therapy.

The term “alkyl” is used herein to refer to both straight- and branched-chain saturated aliphatic hydrocarbon groups having 1-6 carbon atoms; “alkenyl” includes both straight- and branched-chain alkyl groups of 2-6 carbon atoms containing at least one carbon-carbon double bond; “alkynyl” group includes both straight- and branched-chain alkyl groups of 2-6 carbon atoms with at least one carbon-carbon triple bond.

The terms “substituted alkyl”, “substituted alkenyl”, and “substituted alkynyl” refer to alkyl, alkenyl, and alkynyl as containing one or more substituents from the group including halogen, CN, OH, NO₂, amino, aryl, heterocyclic, substituted aryl, substituted heterocyclic, alkoxy, aryloxy, substituted alkyloxy, alkylcarbonyl, alkylcarboxy, alkylamino, arylthio. These substituents may be attached to any carbon of alkyl, alkenyl, or alkynyl group provided that the attachment constitutes a stable chemical moiety.

The term “thioalkyl” is used herein to refer to the SR group, where R is alkyl or substituted alkyl.

The term “alkoxy” is used herein to refer to the OR group, where R is alkyl or substituted alkyl.

The term “aryloxy” is used herein to refer to the OR group, where R is aryl or substituted aryl.

The term “alkylcarbonyl” is used herein to refer to the RCO group, where R is alkyl or substituted alkyl.

The term “alkylcarboxy” is used herein to refer to the COOR group, where R is alkyl or substituted alkyl. This term is also referred to as alkoxycarbonyl.

The term “aminoalkyl” refers to both secondary and tertiary amines wherein the alkyl or substituted alkyl groups may be either same or different and the point of attachment is on the nitrogen atom.

The term “halogen” is defined as Cl, Br, F, and I.

Pharmaceutically acceptable salts can be formed from organic and inorganic acids, for example, acetic, propionic, lactic, citric, tartaric, succinic, fumaric, maleic, malonic, mandelic, malic, phthalic, hydrochloric, hydrobromic, phosphoric, nitric, sulfuric, methanesulfonic, napthalenesulfonic, benzenesulfonic, toluenesulfonic, camphorsulfonic, and similarly known acceptable acids. Salts may also be formed from inorganic bases, preferably alkali metal salts, for example, sodium, lithium, or potassium, and organic bases, such as ammonium, mono-, di-, and trimethylammonium, mono-, di- and triethylammonium, mono-, di- and tripropylammonium (iso and normal), ethyldimethylammonium, benzyldimethylammonium, cyclohexylammonium, benzylammonium, dibenzylammonium, piperidinium, morpholinium, pyrrolidinium, piperazinium, 1-methylpiperidinium, 4-ethylmorpholinium, 1-isopropylpyrrolidinium, 1,4-dimethylpiperazinium, 1-n-butyl piperidinium, 2-methylpiperidinium, 1-ethyl-2-methylpiperidinium, mono-, di- and triethanolammonium, ethyl diethanolammonium, n-butylmonoethanolammonium, tris(hydroxymethyl)methylammonium, phenylmonoethanolammonium, and the like.

The compounds of this invention were be prepared according to the following schemes from commercially available starting materials or starting materials which can be prepared using literature procedures. These schemes show the preparation of representative compounds of this invention.

According to scheme 1, commercially available oxindole 4 is treated with a strong organo-metallic base (e.g., butyl lithium, lithium diisopropylamide, potassium hexamethyldisilazide) in an inert solvent (e.g. THF, diethyl ether) under nitrogen at reduced temperature (ca. −20° C.) (Kende, et al, Synth. Commun. 12, 1, 1982). The resulting di-anion then is treated with excess electrophile such as an alkyl halide, preferably an iodide. If R₁ and R₂ are to be joined such as the product 5 contains a spirocycle at position 3, then the electrophile should be bifunctional, i.e. a diiodide. Subsequent bromination of 5 proceeds smoothly with bromine in acetic acid (an organic co-solvent such as dichloromethane may be added as required) in the presence of sodium acetate, to afford the aryl bromide 6. The bromide 6 is reacted with a palladium salt (e.g., tetrakis(triphenylphosphine)palladium(0) or palladium acetate), in a suitable solvent (e.g., THF, dimethoxyethane, acetone, ethanol or toluene) at room temperature under an inert atmosphere (argon, nitrogen). The mixture is then treated with pyrrole 2-boronic acid (Synthesis 613, 1991) and a base (potassium carbonate, triethylamine, potassium phosphate) in water or fluoride source (cesium fluoride) under anhydrous conditions. Treatment of the biaryl compound 7 with chlorosulfonyl isocyanate followed by an excess of DMF at low temperature produces the protected cyanopyrrole 8. Removal of the tert-butyloxycarbonyl (BOC) protecting group via standard conditions (e.g., TFA/dichloromethane, aqueous NaOH, thermolysis) produces the required final product which is purified by standard means.

As depicted in Scheme 2, an appropriately substituted ortho-amino benzoic acid, or derivative (such as ethyl ester) 10 is treated with a suitable organometallic reagent, e.g., Grignard reagent, in appropriate nonprotic solvents (e.g., THF, ether, toluene) under an inert atmosphere such as argon or nitrogen at −78° C. to room temperature to give ortho-amino carbinol 11. Ring closure of carbinol 11 to yield benzoxazin-2-ones 12 is commonly effected by a condensing agent (e.g., carbonyldiimidazole, phosgene, dimethylcarbonate, diethylcarbonate) in a suitable nonprotic solvent (e.g., THF, ether, toluene) at temperatures in the range of room temperature to 65° C. The pyrrole ring is attached to this platform by employing a suitable coupling reaction (e.g., Suzuki, Stille) to give the biaryl 13. These reactions are performed in the presence of suitable catalyst (e.g., palladium or nickel complexes often with phosphino ligands, e.g., Ph₃P, dppf, dppe or palladium salts such as palladium acetate) and a base: the commonly used bases include (but are not limited to) sodium bicarbonate, sodium carbonate, potassium phosphate, barium carbonate, potassium acetate, or cesium fluoride. The most commonly used solvents in these reactions include benzene, DMF, isopropanol, ethanol, DME, ether, acetone or a mixture of any one of these solvent and water. The coupling reaction generally is executed under an inert atmosphere such as nitrogen or argon at temperatures ranging from room temperature to 95° C. Treatment of the biaryl compound 13 with chlorosulfonyl isocyanate followed by an excess of DMF at low temperature produces the protected cyanopyrrole 14. Removal of the tert-butyloxycarbonyl (BOC) protecting group via standard conditions (e.g., TFA/dichloromethane, aqueous NaOH, thermolysis) produces the required final product 15 which is purified by standard means.

The compounds of this invention are progestational agonists, and are therefore useful as oral contraceptives (male and female), in hormone replacement therapy (particularly when combined with an estrogen), in the treatment of endometriosis, luteal phase defects, benign breast and prostatic diseases and prostatic, breast, ovarian, uterine and endometrial cancers.

The compounds of this invention can be used alone as a sole therapeutic agent or can be used in combination with other agents, such as other estrogens, progestins, or androgens.

The compounds of this invention can be formulated neat or with a pharmaceutical carrier for administration, the proportion of which is determined by the solubility and chemical nature of the compound, chosen route of administration and standard pharmacological practice. The pharmaceutical carrier may be solid or liquid.

A solid carrier can include one or more substances which may also act as flavoring agents, lubricants, solubilizers, suspending agents, fillers, glidants, compression aids, binders or tablet-disintegrating agents; it can also be an encapsulating material. In powders, the carrier is a finely divided solid which is in admixture with the finely divided active ingredient. In tablets, the active ingredient is mixed with a carrier having the necessary compression properties in suitable proportions and compacted in the shape and size desired. The powders and tablets preferably contain up to 99% of the active ingredient. Suitable solid carriers include, for example, calcium phosphate, magnesium stearate, talc, sugars, lactose, dextrin, starch, gelatin, cellulose, methyl cellulose, sodium carboxymethyl cellulose, polyvinylpyrrolidine, low melting waxes and ion exchange resins.

Liquid carriers are used in preparing solutions, suspensions, emulsions, syrups, elixirs and pressurized compositions. The active ingredient can be dissolved or suspended in a pharmaceutically acceptable liquid carrier such as water, an organic solvent, a mixture of both or pharmaceutically acceptable oils or fats. The liquid carrier can contain other suitable pharmaceutical additives such as solubilizers, emulsifiers, buffers, preservatives, sweeteners, flavoring agents, suspending agents, thickening agents, colors, viscosity regulators, stabilizers or osmo-regulators. Suitable examples of liquid carriers for oral and parenteral administration include water (partially containing additives as above, e.g. cellulose derivatives, preferably sodium carboxymethyl cellulose solution), alcohols (including monohydric alcohols and polyhydric alcohols, e.g. glycols) and their derivatives, lethicins, and oils (e.g. fractionated coconut oil and arachis oil). For parenteral administration, the carrier can also be an oily ester such as ethyl oleate and isopropyl myristate. Sterile liquid carriers are useful in sterile liquid form compositions for parenteral administration. The liquid carrier for pressurized compositions can be halogenated hydrocarbon or other pharmaceutically acceptable propellant.

Liquid pharmaceutical compositions which are sterile solutions or suspensions can be utilized by, for example, intramuscular, intraperitoneal or subcutaneous injection. Sterile solutions can also be administered intravenously. The compounds of this invention can also be administered orally either in liquid or solid composition form.

The compounds of this invention may be administered rectally or vaginally in the form of a conventional suppository. For administration by intranasal or intrabronchial inhalation or insufflation, the compounds of this invention may be formulated into an aqueous or partially aqueous solution, which can then be utilized in the form of an aerosol. The compounds of this invention may also be administered transdermally through the use of a transdermal patch containing the active compound and a carrier that is inert to the active compound, is non toxic to the skin, and allows delivery of the agent for systemic absorption into the blood stream via the skin. The carrier may take any number of forms such as creams and ointments, pastes, gels, and occlusive devices. The creams and ointments may be viscous liquid or semisolid emulsions of either the oil-in-water or water-in-oil type. Pastes comprised of absorptive powders dispersed in petroleum or hydrophilic petroleum containing the active ingredient may also be suitable. A variety of occlusive devices may be used to release the active ingredient into the blood stream such as a semipermeable membrane covering a reservoir containing the active ingredient with or without a carrier, or a matrix containing the active ingredient. Other occlusive devices are known in the literature.

The dosage requirements vary with the particular compositions employed, the route of administration, the severity of the symptoms presented and the particular subject being treated. Based on the results obtained in the standard pharmacological test procedures, projected daily dosages of active compound would be 0.02 μg/kg-750 μg/kg. Treatment will generally be initiated with small dosages less than the optimum dose of the compound. Thereafter the dosage is increased until the optimum effect under the circumstances is reached; precise dosages for oral, parenteral, nasal, or intrabronchial administration will be determined by the administering physician based on experience with the individual subject treated. Preferably, the pharmaceutical composition is in unit dosage form, e.g. as tablets or capsules. In such form, the composition is sub-divided in unit dose containing appropriate quantities of the active ingredient; the unit dosage forms can be packaged compositions, for example, packaged powders, vials, ampoules, pre filled syringes or sachets containing liquids. The unit dosage form can be, for example, a capsule or tablet itself, or it can be the appropriate number of any such compositions in package form.

The following provides the preparation of representative compounds of this invention.

EXAMPLE 1 5-(4,4-Dimethyl-2-oxo-1,4-dihydro-2H-benzo[d][1,3]oxazin-6-yl)-1H-pyrrole-2-carbonitrile

A solution of 2-amino-5-bromobenzoic acid (10 g, 46 mmol) in dry THF (200 mL) was treated at −78° C. under nitrogen with a solution of methylmagnesium bromide in ether (3.0 M, 90 mL, 270 mmol). The reaction mixture was slowly warmed to ambient temperature, kept stirring for 48 hours under nitrogen and then poured into a cold 0.5 N aqueous hydrochloride solution (300 mL). The mixture was neutralized with aqueous 1 N sodium hydroxide solution and ethyl acetate (300 mL) was added. The organic layer was separated and aqueous layer was extracted with ethyl acetate (3×100 mL). The combined organic layers were washed with brine and dried (MgSO₄). After removal of solvent in vacuo, the residue was purified by a silica gel flash chromatography (hexane:ethyl acetate/3:2) to give 2-(2-amino-5-bromophenyl)propan-2-ol as an off-white solid (6 g, 57%): mp 62-63° C.; ¹H-NMR (CDCl₃) δ 7.19 (d, 1H, J=2.3 Hz), 7.12 (dd, 1H, J=8.4, 2.3 Hz), 6.51 (d, 1H, J=8.4 Hz), 4.70 (s, 2H), 1.82 (s, 1H), 1.65 (s, 6H).

To a solution of 2-(2-amino-5-bromophenyl)propan-2-ol (18 g, 78 mmol) in dry THF (150 mL) was added 1,1′-carbonyldiimidazole (15.5 g, 94 mmol) under nitrogen. The reaction solution was heated at 50° C. overnight. The solvent was removed in vacuo and the residue was dissolved in ethyl acetate (100 mL). The solution was washed with 1N aqueous hydrochloride solution (2×40 mL), brine (20 mL), and dried with MgSO₄. After removal of the solvent in vacuo, 6-bromo-4,4-dimethyl-1,4-dihydro-benzo[d][1,3]oxazin-2-one was obtained as a white solid (20 g, 100%): mp 199-200° C.; ¹H-NMR (DMSO-d₆) δ 10.32 (s, 1H, D₂O exchangeable), 7.48 (d, 1H, J=2.1 Hz), 7.43 (dd, 1H, J=8.5, 2.1 Hz), 6.84 (d, 1H, J=8.4 Hz), 1.61 (s, 6H).

A solution of 6-bromo-4,4-dimethyl-1,4-dihydro-benzo[d][1,3]oxazin-2-one (5.0 g, 20 mmol) and tetrakis(triphenylphosphine)palladium(0) (580 mg, 0.5 mmol) in toluene (200 mL) was stirred under a flow of nitrogen for 25 min. To the solution was added sequentially 1-tert-butoxycarbonylpyrrole-2-boronic acid (8.24 g, 39 mmol) in absolute ethanol (50 mL) and potassium carbonate (5.39 g, 39 mmol) in water (50 mL). The mixture was heated to 80° C. for 16 hours and allowed to cool. The reaction mixture was poured into aqueous saturated sodium bicarbonate solution (200 mL) and extracted with ethyl acetate (3×200 mL). The organic layers were combined, washed with water (200 mL) and brine (100 mL) and dried over magnesium sulfate. The solution was filtered, concentrated in vacuo, and the residue was purified by flash column chromatography on silica gel (30% ethyl acetate/hexane) to give 2-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-benzo[d][1,3]oxazin-6-yl)-pyrrole-1carboxylic acid tert-butyl ester (4.0 g, 58%) as a tan solid, mp 172-173° C.

To a solution of 2-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-benzo[d][1,3]oxazin-6-yl)-pyrrole-1-carboxylic acid tert-butyl ester (2.0 g, 5.8 mmol) in THF (anhydrous, 50 mL) at −78° C. was added chlorosulfonyl isocyanate (0.66 mL, 6.7 mmol). After 90 minutes, DMF (9 mL, 116 mmol) was added and the reaction was allowed to warm to room temperature. The reaction mixture was poured into water (50 mL) and extracted with ethyl acetate (2×50 mL). The organic layers were combined, washed with brine (50 mL), dried over magnesium sulfate, filtered and concentrated in vacuo. Purification via flash column chromatography on silica gel (30% ethyl acetate/hexane) gave 2-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-benzo[d][1,3]oxazin-6-yl)-5-cyano-pyrrole-1-carboxylic acid tert-butyl ester (1.1 g, 52%) as a white powder, mp 165-167° C. ¹H NMR (d₆-DMSO, 300 MHz) δ 1.36 (s, 9H), 1.61 (s, 6H), 6.44 (d, 1H, J=3.7 Hz), 6.92 (d, 1H, J=8.2 Hz), 7.27-7.32 (m, 2H), 7.36 (‘d’, 1H, J=1.5 Hz), 10.36 (s, 1H). MS (EI) m/z 367 [M]⁺.

2-(4,4-Dimethyl-2-oxo-1,4-dihydro-2H-benzo[d][1,3]oxazin-6-yl)-5-cyano-pyrrole-1-carboxylic acid tert-butyl ester (1 g, 2.7 mmol) was placed in a 25 mL round bottomed flask stoppered with a rubber septum and equipped with a nitrogen inlet and a needle to allow gaseous outflow. A vigorous flow of nitrogen was maintained as the flask was placed in an oil bath and heated to 160° C. After 20 minutes at this temperature, the flask was removed from the oil bath and allowed to cool. The yellow residue was washed into a larger flask with dichloromethane/ethyl acetate and adsorbed onto a small amount of silica gel. Purification by flash column chromatography on silica gel (40% ethyl acetate/hexane) gave the title compound (340 mg, 47%) as a yellow powder, mp 241-242° C. ¹H NMR (d₆-DMSO, 300 MHz) δ 1.65 (s, 6H), 6.67 (d, 1H, J=3.9 Hz), 6.91 (d, 1H, J=8.3 Hz), 6.98 (d, 1H, J=3.9 Hz), 7.61 (dd, 1H, J=1.8, 8.3 Hz), 7.65 (‘d’, 1H, J=1.6 Hz), 10.32 (s, 1H), 12.54 (bs, 1H). MS (EI) m/z 267 M⁺. Anal. Calcd. For C₁₅H₁₃N₃O₂: C, 67.41; H, 4.90; N, 15.72. Found: C, 67.19; H, 4.96; N, 15.35.

EXAMPLE 2 5-(2′-Oxo-2′,3′-dihydrospiro[cyclohexane-1,3′-[3H]indol]-5′-yl-2-cyanopyrrole

A solution of oxindole (25 g, 0.19 mol) in anhydrous tetrahydrofuran (800 mL) was cooled to −20° C., then n-butyllithium (2.5M in hexanes, 152 mL, 0.38 mol) was added slowly followed by N,N,N′,N′-tetramethylethylenediamine (51 mL, 0.38 mol). After 15 min. 1,5-diiodopentane (174 g, 0.54 mol) was added slowly and the mixture was allowed to warm to room temperature. After stirring for 16 hours saturated aqueous ammonium chloride solution (1L) and EtOAc (1L) were added. After 15 minutes, the layers were separated and the aqueous phase was extracted using EtOAc (×2). The combined organic layers were extracted with hydrochloric acid (1N), then washed with brine (500 mL), dried (MgSO₄), and concentrated to obtain an oil. The oil was triturated with hexane (200 mL) and benzene (20 mL). The precipitate was collected and dried in vacuo to obtain spiro[cyclohexane-1,3′-[3H]indol]-2′-(1′H)one (26.3 g, 69.6%) as colorless crystals: mp 110-114° C.; ¹H NMR (DMSO-d₆) δ 1.67 (m, 10H), 6.84 (d, 1H, J=8 Hz) 6.94 (t, 1H, J=8 Hz), 7.17 (t, 1H, J=8 Hz), 7.44 (d, 1H, J=8 Hz), 10.3 (s, 1H).

To a solution of spiro[cyclohexane-1,3′-[3H]indol]-2′(1′H)-one (17.6 g, 9 mmol) in acetic acid (300 mL) was added sodium acetate (8.0 g, 0.1 mol) and bromine (14.6 g, 91 mmol) with stirring. After 30 minutes at room temperature, the reaction mixture was partitioned between water and EtOAc. The aqueous phase was extracted twice with EtOAc. The combined organic layers were washed with water, dried (MgSO₄) and evaporated and the residue was triturated with hexane. The precipitate was collected, and dried in vacuo to obtain 5′-bromospiro[cyclohexane-1,3′-[3H]indol]-2′(1′H)-one (16.5 g, 67%) as off-white crystals: mp 196-199° C.; ¹H NMR (DMSO-d₆) δ 1.62 (m, 10H), 6.8 (d, 1H, J=6.8 Hz), 7.36 (d, 1H, J=8.2, 1.8 Hz), 7.58 (dd, 1H, J=8.2, 1.8 Hz), 10.44 (s, 1H).

To a solution of 5′-bromo-spiro[cyclohexane-1,3′-indolin]-2′-one (3.4 g, 12 mmol) in 1,2-DME (100 mL) under a nitrogen atmosphere, was added tetrakis(triphenylphosphine)palladium(0) (70 mg, 5 mol %). After 15 minutes, 2-borono-1H-pyrrole-1-carboxylic acid, 1-tert butyl ester (1.3 eq, 3.31 g, 15.6 mmol) and a solution of K₂CO₃ (2.3 eq, 3.83 g, 27.6 mmol) in water (5 mL) were added sequentially. The solution was heated to 80° C. for 3 hours and allowed to cool. The reaction mixture was poured into water (200 mL) and extracted with EtOAc (2×100 mL). The organic layers were combined, washed with brine (150 mL) and dried over MgSO₄. The solution was filtered, concentrated in vacuo, and the residue was purified by flash column chromatography on silica gel (eluting with 30% EtOAc/hexane) to give 2-(1′,2′-dihydro-2′-oxospiro[cyclohexane-1,3′-[3H]indol]-5′-yl)-1H-pyrrole-1-carboxylic acid, tert-butyl ester (3.4 g, 76%) as a white powder, mp 177° C. ¹H NMR (CDCl₃; 300 MHz) δ 1.38 (s, 9H), 1.59-1.93 (m, 10H), 6.18 (m, 1H), 6.23 (‘t’, 1H, J=3 Hz), 6.91 (d, 1H, J=8 Hz), 7.21 (d, 1H, J=8 Hz), 7.34 (m, 1H), 7.44 (s, 1H), 8.33 (br s, 1H, D₂Oex). MS ((+)-APCI) m/z 367 [(M+H)⁺]. Anal. Calcd for C₂₂H₂₆N₂O₃: C, 72.11; H, 7.15; N, 7.64. Found: C, 71.7; H, 7.16; N, 7.5.

To a solution of 2-(1′,2′-dihydro-2′-oxospiro[cyclohexane-1,3′-[3H]indol]-5-yl)-1H-pyrrole-1-carboxylic acid, tert-butyl ester (0.75 g, 2 mmol) in THF (anhydrous, 20 mL) at −78° C. was added chlorosulfonyl isocyanate (1.15 eq, 0.23 mL, 2.3 mmol). After 90 min, DMF (20 eq, 3.6 mL, 46 mmol) was added and the reaction was allowed to warm to room temperature. The reaction mixture was poured into water (50 mL) and extracted with ethyl acetate (2×50 mL). The organic layers were combined, washed with brine (50 mL), dried over magnesium sulfate, filtered and concentrated in vacuo. Purification via flash column chromatography on silica gel (30% ethyl acetate/hexane) gave 5-(2′-oxo-2′,3′-dihydrospiro[cyclohexane-1,3′-[3H]indol]-5′-yl-2-cyanopyrrole-1-carboxylic acid, tert-butyl ester (0.5 g, 63%) as an oil which crystallized from acetone to give white crystals, mp 156° C. ¹H NMR (d₆-DMSO, 400 MHz) δ 1.32 (s, 9H), 1.50 (m, 3H), 1.60-1.70 (m, 5H), 1.75-1.85 (m, 2H), 6.38 (d, 1H, J=3.7 Hz), 6.87 (d, 1H, J=7.9 Hz), 7.18 (dd, 1H, J=1.5, 7.9 Hz), 7.27 (d, 1H, J=3.7 Hz), 7.48 (d, 1H, J=1.8 Hz), 10.42 (bs, 1H). MS (EI) m/z 391 (M⁺). Anal. Calcd for C₂₃H₂₅N₃O₃: C, 70.57; H, 6.44; N, 10.73. Found: C, 69.82; H, 6.46; N, 10.43.

5-(2′-Oxo-2′,3′-dihydrospiro[cyclohexane-1,3′-[3H]indol]-5′-yl-2-cyanopyrrole-1-carboxylic acid, tert-butyl ester (0.25 g, 0.8 mmol) was placed in a 5 mL round bottomed flask stoppered with a rubber septum and equipped with nitrogen inlet and a needle to allow gaseous outflow. A vigorous flow of nitrogen was maintained as the flask was placed in an oil bath and heated to 180° C. After 5 minutes at this temperature, the flask was removed from the oil bath and allowed to cool. The black residue was washed into a larger flask with acetone and adsorbed onto a small amount of silica gel. Purification by flash column chromatography on silica gel (eluting with 30% EtOAc/hexane) gave the title compound (95 mg, 51 %) as a yellow oil which crystallized from dichloromethane to give a grey powder, mp 239 ° C. (dec). ¹H NMR (DMSO-d₆; 300 MHz) δ 1.40-1.90 (m, 10H), 6.60 (m, 1H), 6.88 (d, 1H, J=8.1 Hz), 6.95 (m, 1H), 7.56 (dd, 1H, J=1.8, 8.1 Hz), 7.78 (d, 1H, J=1.3 Hz), 10.42 (s, 1H), 12.50 (s, 1H). MS (EI) m/z 291 (M⁺). Anal. Calcd for C₁₈H₁₇N₃O₁: C, 74.20; H, 5.88; N, 14.42. Found: C, 66.63; H, 5.52; N, 12.46.

EXAMPLE 3 2-(3,3-Dimethyl-2-oxo-2,3-dihydro-1H-indol-5-yl)-2-cyanopyrrole

To a solution 2-(3,3-dimethyl-2-oxo-2,3-dihydro-1H-indol-5-yl)-pyrrole-1-carboxylic acid tert-butyl ester (0.39 g, 1.2 mmol) in THF (anhydrous, 9 mL) at −78° C. was added chlorosulfonyl isocyanate (1.15 eq, 0.12 mL, 1.4 mmol). After 120 min, DMF (20 eq, 1.8 mL, 23 mmol) was added and the reaction was allowed to warm to room temperature. The reaction mixture was poured into water (25 mL) and extracted with ethyl acetate (2×50 mL). The organic layers were combined, washed with brine (50 mL), dried over magnesium sulfate, filtered and concentrated in vacuo. Purification via flash column chromatography on silica gel (1:3 ethyl acetate/hexane) gave 2-(3,3-dimethyl-2-oxo-2,3-dihydro-1H-indol-5-yl)-2-cyanopyrrole-1-carboxylic acid tert-butyl ester (0.21 g, 50%) as a white solid: mp 158.6. ¹H NMR (DMSO-d₆; 300 MHz) δ 1.27 (s, 6H), 1.33 (s, 9H), 6.40 (d, 1H, J=3.8 Hz), 6.90 (d, 1H, J=8.0 Hz), 7.19 (dd, 1H, J=1.8, 8.0 Hz), 7.30 (d, 1H, J=1.5 Hz), 10.50 (s, 1H). MS m/z 350 (M−H)⁻. Calcd for C₁₉H₂₂N₂O₃: C, 68.36; H, 6.02; N, 11.96. Found: C, 66.79; H, 6.03; N, 11.02.

2-(3,3-Dimethyl-2-oxo-2,3-dihydro-1H-indol-5-yl)-pyrrole-1-carboxylic acid tert-butyl ester (0.18 g, 0.51 mmol) was placed in a 50 mL round bottomed flask stoppered with a rubber septum and equipped with a nitrogen inlet and a needle to allow gaseous outflow. A vigorous flow of nitrogen was maintained as the flask was placed in an oil bath and heated to 160° C. After 10 minutes at this temperature, the flask was removed from the oil bath and allowed to cool. The black residue was washed into a larger flask with acetone and adsorbed onto a small amount of flurosil. Purification by flash column chromatography on silica gel (eluting with 1:3 acetone: hexane) gave the title compound (118 mg, 92%) as a white solid mp 255.9-257.9° C. ¹H NMR (DMSO-d₆; 300 MHz) δ 1.29 (s, 6H), 6.60 (m, 1H), 6.89 (d, 1H, J=8.0 Hz), 6.96 (m, 1H), 7.55 (dd, 1H, J=1.4, 8.1 Hz), 7.69 (bs, 1H), 10.47 (s, 1H), 12.48 (s, 1H). MS m/z 250 (M−H)⁻. Calcd for C₂₀H₂₁N₃O₃: C, 71.7; H, 5.21; N, 16.72. Found: C, 71.16; H, 5.58; N, 16.09.

EXAMPLE 4 5-(2′-Oxo-2′,3′-dihydrospiro[cyclopentane-1,3′-[3H]indol]-5′-yl-2-cyanopyrrole

A solution of 5′-bromospiro[cyclopentane-1,3′-[3H]indol]-2′(1H)-one (2.0 g, 7.5 mmol) and tetrakis(triphenylphosphine)palladium(0) (430 mg, 0.3 mmol) in ethylene glycol dimethyl ether (50 mL) was stirred under a flow of nitrogen for 15 minutes. To the solution was added sequentially 1-t-butoxycarbonylpyrrole-2-boronic acid (2.1 g, 9.7 mmol) and potassium carbonate (2.4 g, 17 mmol) in water (10 mL). The mixture was heated to 80° C. for 3 hours and allowed to cool. The reaction mixture was poured into water (50 mL) and extracted with ethyl acetate (3×50 mL). The organic layers were combined, washed with brine (30 mL) and dried over magnesium sulfate. The solution was filtered and concentrated in vacuo. Crystallization from 20% ethyl acetate/hexane gave 2-(1′,2′-dihydro-2′-oxospiro [cyclopentane-1,3′-[3H]indol]-5′-yl)-1H-pyrrole-1-carboxylic acid, tert-butyl ester (2.2 g, 83%) as a white powder, mp 179-180.5° C. ¹H NMR (DMSO-d₆, 400 MHz) δ 1.30 (s, 9H), 1.75-1.98 (m, 8H), 6.16 (dd, 1H, J=1.8, 3.3 Hz), 6.22 (‘t’, 1H, J=3.3, 3.3 Hz), 6.79 (d, 1H, J=7.9 Hz), 7.08 (dd, 1H, J=1.8, 7.9 Hz), 7.14 (‘d’, 1H, J=1.5 Hz), 7.28 (dd, J=1.9, 3.3 Hz), 10.30 (s, 1H). MS (EI) m/z 352 [M⁺]. Anal. Calcd for C₂₁H₂₄N₂O₃: C, 71.57; H, 6.86; N, 7.95. Found: C, 71.08; H, 6.83; N, 7.74.

To a solution of 2-(1′,2′-dihydro-2′-oxospiro[cyclohexane-1,3′-[3H]indol]-5′-yl)-1H-pyrrole-1-carboxylic acid, tert-butyl ester (2.2 g, 6.0 mmol) in THF (anhydrous, 25 mL) was added at −78° C. chlorosulfonyl isocyanate (0.63 mL, 7.0 mmol). After 90 minutes, dimethylformamide (11 mL, 140 mmol) was added and the reaction was allowed to warm to room temperature. The reaction mixture was poured into water (50 mL) and extracted with ethyl acetate (2×50 mL). The organic layers were combined, washed with brine (50 mL), dried over magnesium sulfate, filtered and concentrated in vacuo. Purification via flash column chromatography on silica gel (30% ethyl acetate/hexane) gave 5-(2′-oxo-2′,3′-dihydrospiro[cyclopentane-1,3′-[3H]indol]-5′-yl-2-cyanopyrrole-1-carboxylic acid, tert-butyl ester (1.7 g, 75%) as white crystals, mp 167-169° C. ¹H NMR (DMSO-d₆, 400 MHz) δ 1.34 (s, 9H), 1.75-1.98 (m, 8H), 6.39 (d, 1H, J=3.7 Hz), 6.84 (d, 1H, J=7.9 Hz), 7.17 (dd, 1H, J=1.8, 7.9 Hz), 7.28 (‘t’, 2H), 10.41 (s, 1H). MS (ESI) mn/z 376 [M−H]⁻. Anal. Calcd. for C₂₂H₂₃N₃O₃: C, 70.01; H, 6.14; N, 11.13. Found: C, 69.67; H, 6.38; N, 11.04.

5-(2′-Oxo-2′,3′-dihydrospiro[cyclopentane-1,3′-[3H]indol]-5′-yl-2-cyanopyrrole-1-carboxylic acid, tert-butyl ester (1 g, 2.7 mmol) was placed in a 25 mL round bottomed flask stoppered with a rubber septum and equipped with nitrogen inlet and a needle to allow gaseous outflow. A vigorous flow of nitrogen was maintained as the flask was placed in an oil bath and heated to 165° C. After 20 minutes at this temperature, the flask was removed from the oil bath and allowed to cool. Crystallization from ethyl ether gave the title compound (600 mg, 79%) as a yellow powder, mp 285-286° C. ¹H NMR (DMSO-d₆, 400 MHz) δ 1.75-2.03 (m, 8H), 6.60 (dd, 1H, J=2.4, 3.7 Hz), 6.84 (d, 1H, J=8.1 Hz), 6.94 (dd, 1H, J=2.4, 3.7 Hz), 7.52 (dd, 1H, J=1.8, 8.1 Hz), 7.60 (d, 1H, J=1.8 Hz), 10.38 (s, 1H), 12.45 (s, 1H). MS (ESI) m/z 276 [M−H]⁻. Anal. Calcd. For C₁₇H₁₅N₃O: C, 73.63; H, 5.45; N, 15.15. Found: C, 73.24; H, 5.34; N, 14.96.

EXAMPLE 5 5-(4,4-Dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1-methyl-1H-pyrrole-2 carbonitrile

To a solution of 5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1H-pyrrole-2-carbonitrile (1 eq, 71 mg, 0.27 mmol) in dimethylformamide (0.5 mL) was added potassium carbonate (5 eq, 0.18 g, 0.1.35 mmol). After 10 minutes, iodomethane (3 eq, 0.05 mL, 0.81 mmol) was added and the suspension was stirred for 2h, poured into water (5 mL) and extracted with ethyl acetate (3×5 mL). The layers were separated, the aqueous layer was extracted with ethyl acetate (3×10 mL) and the combined organic layer was washed with brine, dried over MgSO₄ and purified by flash column chromatography on silica gel eluting with 30% ethyl acetate/hexane to give 5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1-methyl-1H-pyrrole-2-carbonitrile (30 mg, 41%) as a white solid. ¹H NMR (300 MHz, d₆-DMSO) δ 1.64 (s, 6H), 3.71 (s, 3H), 6.33 (d, 1H, J=4.1 Hz), 6.98 (d, 1H, J=8.0 Hz), 7.03 (d, 1H, J=4.1 Hz), 7.39 (m, 2H), 10.39 (s, 1H). MS (APCI (−)) m/z 280 (M−H)⁻. Anal. calcd for C₁₆H₁₅N₃O₂, C, 68.3, H, 5.37, N, 14.9. Found, C, 68.4, H, 5.51, N, 14.6.

EXAMPLE 6 General Method A 5-(4,4-Dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1-ethyl-1H-pyrrole-2-carbonitrile

To a solution of 5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1H-pyrrole-2-carbonitrile (1.3 g, 5 mmol) in dimethylformamide (25 ml) was added potassium carbonate (1 g, 7.5 mmol), and iodoethane (0.4 ml, 5.1 mmol), and the mixture was stirred at room temperature for 3 hours. Ethylacetate and water were added, the ethylacetate layer was separated, dried over magnesium sulfate, and concentrated in vacuo. The residue was recrystallized from ethylacetate/hexane to afford the title compound, m.p. 200-202° C. (0.4 g, 27%); ¹H-NMR (DMSO-d₆) δ 1.25 (t, J=7.2 Hz, 3H), 1.64 (s, 6H), 4.07 (q, J=7.2 Hz, 2H), 6.29 (d, J=4.1 Hz, 1H), 7.0 (d, J=8 Hz, 1H), 7.05 (d, J=4.1 Hz, 1H), 7.34 (m, 2H), 10.42 (s, 1H). MS (ESI (−)) m/z 294 (M−H)⁻

EXAMPLE 7 5-(4,4-dimethyl-2-oxo-1,4-Dihydro-2H-3,1-benzoxazin-6-yl)-1-prop-2-ynyl-1H-pyrrole-2-carbonitrile

5-(4,4-Dimethyl-2-oxo-1,4,dihydro-2H-3,1-benzoxazin-6-yl)-1H-pyrrol-2-carbonitrile (0.74 g, 2.8 mmol) and propargylbromide (0.5 g, 4.2 mmol) were reacted, according to General Method A, to afford the title compound, m.p. 222-224° C. (0.13 g, 15%). ¹H-NMR (DMSO-d₆) δ 1.65 (s, 6H), 3.64 (t, J=2.3 Hz, 1H), 4.85 (d, J=2.3 Hz, 2H), 6.37 (d, J=4 Hz, 1H), 7.01 (d, J=8.2 Hz, 1H), 7.11 (d, J=4 Hz, 1H), 7.43 (m, 2H), 10.45 (s, 1H), MS (APCI (−)) m/z 304 (M−H)⁻

EXAMPLE 8 tert-butyl[2-cyano-5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1H-pyrrol-1-yl]acetate

5-(4,4-Dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1H-pyrrol-2-carbonitrile (5.4 g, 20 mmol) and tert-butylbromoacetate (4.64 g, 22 mmol) were reacted, according to General Method A, to afford the title compound, m.p. 188-190° C. (3 g, 40%). ¹H-NMR (DMSO-d₆) δ 1.35 (s, 9H), 1.62 (s, 6H), 4.8 (s, 2H), 6.35 (d, J=4.3 Hz, 1H), 6.98 (d, J=8.1 Hz, 1H), 7.09 (d, J=4.3 Hz, 1H), 7.26 (m, 2H), 10.42 (s, 1H), MS (APCI (−)) m/z 380 (M−H)⁻

EXAMPLE 9 [2-Cyano-5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1H-pyrrol-1yl]acetic acid

A solution of tert-butyl[2-cyano-5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1H-pyrrol-1-yl]acetate (2.2 g, 5.8 mmol), and sodium hydroxide (1.6 g, 40 mmol) in ethanol (200 ml) was heated to reflux for 2 hours. After cooling to room temperature the mixture was acidified with diluted hydrochloric acid, and extracted with ethylacetate. The ethylacetate solution was dried over magnesium sulfate, filtered, and concentrated in vacuo. Recrystallization from ethylacetate/hexane afforded the title compound, m.p. 207-209° C. (1.2 g, 64%); ¹H-NMR (DMSO-d₆) δ 1.61 (s, 6H), 4.77 (s, 2H), 6.35 (d, J=4 Hz, 1H), 6.98 (d, J=8.1 Hz, 1H), 7.09 (d, J=4.1 Hz, 1H), 7.26 (m, 2H), 10.43 (s, 1H), MS (APCI (−)) m/z 324 (M−H)⁻.

EXAMPLE 10 2-[2-cyano-5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1H-pyrrol-1-yl]-N-[2-(3-ethoxy-4-methoxyphenyl)ethyl]acetamide

A solution of [2-cyano-5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1H-pyrrol-1-yl]acetic acid (0.6 g, 1.8 mmol), 3-ethoxy-4-methoxyphenylethylamine (0.36 g, 1.9 mmol), diiso-propylethylamine (0.26 g, 2 mmol), and O-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate (0.7 g, 1.8 mmol) in dimethylformamide (20 ml) was stirred at room temperature for 20 hours. The mixture was diluted with water and extracted with ethylacetate. The ethylacetate solution was washed with brine, dried over magnesium sulfate, and concentrated in vacuo. The residue was recrystallized from ethanol to afford the title compound, m.p. 160-162° C. (0.2 g, 22%): ¹H-NMR (DMSO-d₆) δ 1.3 (t, J=6.9 Hz, 3H), 1.59 (s, 6H), 2.61 (t, 2H, J=7 Hz), 3.29 (q, J=6.9 Hz, 2H), 3.71 (s, 3H), 3.97 (q, J=6.9 Hz, 2H), 4.6 (s, 2H), 6.32 (d, J=5.1 Hz, 1H), 6.65 (dd, J=7.6, 2.0 Hz, 1H), 6.77 (d, J=2.3, 1H), 6.83 (d, J=8.3 Hz, 1H), 6.96 (d, J=8.7 Hz, 1H), 7.05 (d, J=4.1 Hz, 1H), 7.26 (m, 2H), 8.3 (t, J=6 Hz, 1H), 10.42 (s, 1H), MS (APCI (+)) m/z 503 (M+H)⁺

EXAMPLE 11 5-(4,4-Dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazine-6-yl)-1-pentyl-1H-pyrrole-2-carbonitrile

5-(4,4-Dimethyl-oxo-1,4-dihydro-2H-3,1-benzoxazine-6-yl)-1H-pyrrole-carbonitrile (1.94 g, 7.3 mmol) was reacted, according to General Method A, with 1-iodopentane (1.5 g, 7.6 mmol) to afford the title compound, m.p. 128-131° C. (0.2 g, 8%); ¹H-NMR (DMSO-d₆) δ 0.73 (t, J=7.3 Hz, 3H), 1.05 (m, 2H), 1.14 (m, 2H), 1.57 (m, 2H), 1.63 (s, 6H), 4.04 (t, J=7.5 Hz, 2H), 6.28 (d, J=4 Hz, 1H), 6.98 (d, J=7.9 Hz, 1H), 7.04 (d, J=4.5 Hz, 1H), 7.33 (dd, J=8.9, 2.0 Hz, 1H), 7.37 (d, J=2.2 Hz, 1H), 10.41 (s, 1H), MS (APCI (−)) m/z 336 (M−H)⁻

EXAMPLE 12 5-(1,4,4-trimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1H-pyrrole-2-carbonitril

tert-Butyl 2-cyano-5-(1,4,4-trimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1H-pyrrole-1-carboxylate.

To a solution of 2-(4,4-Dimethyl-2-oxo-1,4-dihydro-2H-benzo[d][1,3]oxazin-6-yl)-5-cyano-pyrrole-1-carboxylic acid tert-butyl ester (0.5 g, 1.4 mmol, 1 eq) in DMF (anhydrous, 25 mL) was added NaH (60% dispersion in oil, 65 mg, 1.6 mmol, 1.2 eq) at 0° C. After 15 min, methyl iodide (0.25 mL, 4.1 mmol, 3 eq) was added and the reaction was allowed to warm to room temperature over night. The reaction mixture was poured into water (50 mL) and extracted with ethyl acetate (2×50 mL). The organic layers were combined, washed with brine (50 mL), dried over magnesium sulfate, filtered and concentrated in vacuo to give the product (0.5 g, 94%) as an off-white solid, mp 143-145° C.: ¹H NMR (300 MHz, d₆-DMSO) δ 1.38 (s, 9H), 1.62 (s, 6H), 3.33 (s, 3H), 6.48 (d, 1H, J=3.8 Hz), 7.13 -7.16 (‘dd’, 1H), 7.33 (d, 1H, J=3.8 Hz), 7.40-7.43 (m, 2H). MS (ESI (+)) [M+H]⁺=382. Anal. calcd. for C₂₁H₂₃N₃O₄: C, 66.13; H, 6.08; N, 11.02. Found: C, 65.46; H, 6.16, N, 11.02.

tert-Butyl 2-cyano-5-(1,4,4-trimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1H-pyrrole-1-carboxylate (180 mg, 0.47 mmol) was placed in a 25 mL round bottomed flask stoppered with a rubber septum and equipped with nitrogen inlet and a needle to allow gaseous outflow. A vigorous flow of nitrogen was maintained as the flask was placed in an oil bath and heated to 150° C. After 20 minutes at this temperature, the flask was removed from the oil bath and allowed to cool. To the solid was added acetone/dichloromethane. The solid was filtered to give the product (100 mg, 76%) as an off-white solid, mp 256-7° C. (dec.): ¹H NMR (300 MHz, d₆-DMSO) δ 1.65 (s, 6H), 3.33 (s, 3H), 6.74 (dd, 1H, J=2.6, 3.6 Hz), 7.00 (dd, 1H, J=2.2, 3.8 Hz), 7.15 (d, 1H, J=8.5 Hz), 7.67 (d, 1H, J=1.9 Hz), 7.73 (dd, 1H, J=1.19, 8.5 Hz), 12.62 (s, 1H). MS (ESI (+)) [M+H]⁺=282. Anal. calcd. for C₁₆H₁₅N₃O₂: C, 68.31; H, 5.37; N, 14.94. Found: C, 67.87; H, 5.42, N, 14.75.

EXAMPLE 13 4-Bromo-5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1-methyl-1H-pyrrole-2-carbonitrile

To a solution of tert-butyl 6-(5-cyano-1-methyl-1H-pyrrol-2-yl)-4,4-dimethyl-2-oxo-2H-3,1-benzoxazine-1(4H)-carboxylate (1 eq, 1.94 g, 5.10 mmol) in THF (150 mL) at −78° C. was added N-bromosuccinimide (1.1 eq, 1.0 g, 5.61 mmol). The solution was allowed to warm and stir for 16 hours. Pyridine (1 mL) was added and the mixture was poured into water (150 mL), the layers were separated, the aqueous layer was extracted with ethyl acetate (3 ×10 mL) and the combined organic layer was washed with brine, dried over MgSO₄ and concentrated in vacuo. The product, tert-butyl 6-(3-bromo-5-cyano-1-methyl-1H-pyrrol-2-yl)-4,4-dimethyl-2-oxo-2H-3,1-benzoxazine-1(4H)-carboxylate was obtained by crystallization from 20% ethyl acetate/hexane as a white crystalline solid. ¹H NMR (300 MHz, d₆-DMSO) δ 1.56 (s, 9H), 1.71 (s, 6H), 3.65 (s, 3H), 7.30 (s, 1H), 7.44 (d, 1H, J=8.4 Hz), 7.52 (d, 1H, J=8.4 Hz), 7.55 (s, 1H). M/z (ESI (+)) 461 (M+H)⁺. Anal. calcd for C₂₁H₂₂N₃O₄, C, 54.8, H, 4.82, N, 9.13. Found, C, 54.9, H, 4.86, N, 9.1.

A solution of tert-butyl 6-(3-bromo-5-cyano-1-methyl-1H-pyrrol-2-yl)-4,4-dimethyl-2-oxo-2H-3,1-benzoxazine-1(4H)-carboxylate (1 eq, 0.4 g, 0.87 mmol) in THF was added to a solution of sodium ethoxide (3 eq, 0.18 g, 2.6 mmol) in ethanol (10 mL). The solution was heated at 80° C. for 1 hour, then cooled to room temperature, and concentrated in vacuo. The residue was dissolved in THF (10 mL) and 4N HCl (10 mL) was added. After heating to 60° C. for 16 hours the solution was cooled, poured into water and the layers were separated. The aqueous layer was extracted with ethyl acetate (3×10 mL) and the combined organic layer was washed with brine, dried over MgSO₄ and concentrated in vacuo. The product, 4-bromo-5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1-methyl-1H-pyrrole-2-carbonitrile (0.17 g, 54%) was obtained by crystallization from 20% ethyl acetate/hexane. ¹H NMR (300 MHz, d₆-DMSO) δ 1.64 (s, 6H), 3.62 (s, 3H), 7.02 (d, 1H, J=8.2 Hz), 7.34 (s, 1H), 7.35 (dd, 1H, J=1.3, 8.2 Hz), 7.40 (s, 1H), 10.47 (s, 1H). MS (ESI (−)) m/z 358/360 (M−H)⁻. Anal. calcd for C₁₆H₁₄N₃O₂Br, C, 53.4, H, 3.92, N, 11.7. Found, C, 52.6, H, 3.82, N, 11.2.

EXAMPLE 14 5-(4,4-Dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1,4-dimethyl-1H-pyrrole-2-carbonitrile

A solution of 4-bromo-5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1-methyl-1H-pyrrole-2-carbonitrile (70 mg, 0.2 mmol), PhCNPdCl(PPh₃)₂ (cat., 7 mg) and tetramethyltin (10 eq, 0.35 g, 2 mmol) in HMPA (3 mL) was heated to 110° C. for 5 days. The solution was allowed to cool, poured into water (20 mL) and extracted with ethyl acetate (3×5 mL). The combined organic layer was washed with brine, dried over MgSO₄ and purified by flash column chromatography on silica gel eluting with 30% ethyl acetate/hexane to give 5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1,4-dimethyl-1H-pyrrole-2-carbonitrile (36 mg, 63%) as a white solid. ¹H NMR (300 MHz, d₆-DMSO) δ 1.64 (s, 6H), 1.97 (s, 3H), 3.56 (s, 3H), 6.87 (s, 1H), 7.00 (d, 2H, J=8.1 Hz), 7.28 (dd, 1H, J=8.1, 1.6 Hz), 7.32 (s, 1H), 10.40 (s, 1H) MS (ESI (−)) 294 (M−H)⁻. Anal. calcd for C₁₇H₁₇N₃O₂, C, 69.1, H, 5.8, N,14.2. Found, C, 69.1, H, 5.72, N, 14.0.

EXAMPLE 15 tert-Butyl 5-cyano-2-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-3-nitro-1H-pyrrole-1-carboxylate

To a solution of 2-(4,4-Dimethyl-2-oxo-1,4-dihydro-2H-benzo[d][1,3]oxazin-6-yl)-5-cyano-pyrrole-1-carboxylic acid tert-butyl ester (3.0 g, 8.2 mmol, 1 eq) in acetic anhydride (50 mL) was added Cu(NO₃)_(2.)2.5 H₂O (1.04 g, 4.5 mmol, 0.55 eq). After the reaction mixture stirred at room temperature for 24 hours, it was poured into saturated aqueous sodium bicarbonate solution (100 mL) and extracted with ethyl acetate (2×100 mL). The organic layers were combined, washed with water (50 mL) and brine (50 mL), dried over magnesium sulfate, filtered and concentrated in vacuo. Purification by flash column chromatography (20% ethyl acetate/hexane) on silica gel gave the product as a yellow solid (0.54 g, 16%). ¹H NMR (500 MHz, d₆-DMSO) δ 1.25 (s, 9H), 1.60 (s, 6H), 6.97 (d, 1H, J=8.2 Hz), 7.38 (dd, 1H, J=1.8, 8.2 Hz), 7.49 (d, 1H, J=1.8 Hz), 8.09 (s, 1H), 10.47 (s, 1H). MS (ESI (−)) [M−H]⁻=411. Anal. calcd. for C₂₀H₂₀N₄O₆: C, 58.25; H, 4.89; N, 13.59. Found: C, 58.72; H, 5.14, N, 13.39.

EXAMPLE 16 4-Amino-5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1H-pyrrole-2-carbonitrile

A solution of 4-nitro-5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1H-pyrrole-2-carbonitrile (0.4 g, 1.28 mmol) in ethanol/water (5:1, 20 mL) was treated sequentially with zinc powder (2.5 wt, 1.0 g) and ammonium chloride (5 wt, 2.0 g). The suspension was heated at 80° C. or 30 min, cooled to room temperature, poured into water (30 mL) and extracted with ethyl acetate (3×15 mL). The combined organic layer was washed with brine, dried over MgSO₄ and purified by flash column chromatography on silica gel eluting with ethyl acetate to give 4-amino-5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1H-pyrrole-2-carbonitrile (0.29 g, 80%) as a yellow solid. ¹H NMR (500 MHz, d₆-DMSO) δ 81.63 (s, 6H), 4.29 (s, 2H), 6.39 (s, 1H), 6.89 (d, 1H, J=8.1 Hz), 7.49 (s, 1H), 7.52 (dd, 1H, J=8.1 and 2.3 Hz), 10.25 (s, 1H), 11.76 (s, 1H). MS (ESI (−)) m/z 281 (M−H)⁻. Anal. calcd for C₁₅H₁₄N₄O₂, C, 63.8, H, 5.00, N, 19.9. Found, C, 63.7, H, 5.10, N, 19.82

EXAMPLE 17 5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-3-nitro-1H-pyrrole-2-carbonitrile

To 4,4-Dimethyl-6-(5-cyano-1H-pyrrol-2-yl)-1,4-dihydrobenzo[d][1,3]oxazin-2-one (0.3 g, 1.2 mmol, 1 eq) in acetic anhydride (7.3 mL) was added Cu(NO₃)₂.2.5 H₂O (0.15 g, 0.65 mmol, 0.55 eq). After the reaction mixture stirred at room temperature for 2 hours, it was poured into saturated aqueous sodium bicarbonate solution (50 mL) and extracted with ethyl acetate (2×50 mL). The organic layers were combined, washed with water (50 mL) and brine (50 mL), dried over magnesium sulfate, filtered and concentrated in vacuo. The residue crystallized from dichloromethane/acetone to give the product as a yellow solid (48 mg, 13%). The filtrate (0.3 g) was placed aside. ¹H NMR (300 MHz, d₆-DMSO) δ 1.65 (s, 6H), 6.94 (d, 1H, J=8.3 Hz), 7.51 (s, 1H), 7.73 (d, 1H, J=8.3 Hz), 7.78 (s, 1H), 10.46 (s, 1H), 13.84 (s, 1H). MS (ESI (−)) [M−H]⁻m/z 311. Anal. calcd. for C₁₅H₁₂N₄O₄: C, 57.69; H, 3.87; N, 17.94. Found: C, 57.91; H, 3.96, N, 17.41.

EXAMPLE 18 3-amino-5 -(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1H-pyrrole-2-carbonitrile

To 5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-3-nitro-1H-pyrrole-2-carbonitrile (0.14 g, 0.45 mmol) in EtOH/H₂O (5:1, 20 mL:4 mL) was added Zn powder (0.35 g, 5.3 mmol) and NH₄Cl (0.70 g, 13 mmol) and the mixture was heated to 60° C. for 25 minutes. After cooling to room temperature and stirring 24 h, the reaction mixture was diluted with ethyl acetate (100 mL) and filtered through a pad of celite. The filtrate was washed with water (50 mL) and brine (50 mL), dried over magnesium sulfate, filtered and concentrated in vacuo. Purification by flash column chromatography (60% ethyl acetate/hexane) on silica gel gave the product as an orange foam (30 mg, 24%). ¹H NMR (500 MHz, d₆-DMSO) δ 1.63 (s, 6H), 5.01 (s, 2H), 5.95 (d, 1H, J=2.9 Hz), 6.87 (d, 1H, J=8.3 Hz), 7.48 (dd, 1H, J=2.0, 8.3 Hz), 7.54 (d, 1H, J=2.0 Hz), 10.30 (s, 1H), 11.17 (d, 1H, J=2.5 Hz). MS (ESI) [M−H]⁻ m/z 281.

EXAMPLE 19 5-(4,4-Dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1,3,4-trimethyl-1H-pyrrol-2-carbonitrile

To a solution of 5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1,4-dimethyl-1H-pyrrole-2-carbonitrile (1 eq, 0.15 g, 0.51 mmol) in THF (5 mL) at −78° C. was added N-bromosuccinimide (1.1 eq, 0.1 g, 0.56 mmol). The solution was allowed to warm and stir for 16 hours. Pyridine (1 mL) was added and the mixture was poured into water (15 mL), the layers were separated, the aqueous layer was extracted with ethyl acetate (3×10 mL) and the combined organic layer was washed with brine, dried over MgSO₄ and concentrated in vacuo. The product, 5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-3-bromo-1,4-dimethyl-1H-pyrrole-2-carbonitrile was obtained by crystallization from 20% ethyl acetate/hexane as a white crystalline solid. ¹H NMR (300 MHz, d₆-DMSO) δ 1.64 (s, 6H), 1.93 (s, 3H), 3.57 (s, 3H), 7.01 (d, 1H, J=8 Hz), 7.31 (dd, 1H, J=1.95, 8 Hz), 7.35 (s, 1H), 10.43 (s, 1H). MS m/z (ESI (−)) 372/374 (M−H)⁻. Anal. calcd for C₁₇H₁₆N₃O₂, C, 54.6, H, 4.31, N, 11.2. Found, C, 54.8, H, 4.42, N, 11.1.

A solution of 5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-3-bromo-1,4-dimethyl-1H-pyrrole-2-carbonitrile (0.11 g, 0.29 mmol), PhCNPdCl(PPh₃)₂ (cat., 11 mg) and tetramethyltin (10 eq, 0.53 g, 2.9 mmol) in HMPA (3 mL) was heated to 110° C. for 5 days. The solution was allowed to cool, poured into water (20 mL) and extracted with ethyl acetate (3×15 mL). The combined organic layer was washed with brine, dried over MgSO₄ and purified by flash column chromatography on silica gel eluting with 30% ethyl acetate/hexane to give 5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1,3,4-trimethyl-1H-pyrrole-2-carbonitrile (77 mg, 85%) as a white solid. ¹H NMR (300 MHz, d₆-DMSO) δ 1.63 (s, 6H), 1.87 (s, 3H), 2.49 (s, 3H), 3.50 (s, 3H), 6.99 (d, 1H, J=8.2 Hz), 7.25 (dd, 1H, J=8.2, 1.4 Hz), 7.29 (s, 1H), 10.39 (s, 1H). MS (ESI (−)) 308 (M−H)⁻. Anal. calcd for C₁₈H₁₉N₃O₄, C, 69.9, H, 6.19, N, 13.6. Found, C, 68.8, H, 6.22, N, 12.9

EXAMPLE 20 4-bromo-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1H-pyrrole-2-carbonitrile

To 4,4-Dimethyl-6-(5-cyano-1H-pyrrol-2-yl)-1,4-dihydrobenzo[d][1,3]oxazin-2-one (0.625 g, 2.3 mmol, 1 eq) in THF (anhydrous, 60 mL) was added NBS (0.46 g, 2.5 mmol, 1.1 eq) at −78° C. After 1 hour, the reaction was warmed to room temperature, poured into water (100 mL) and extracted with ethyl acetate (2×100 mL). The organic layers were combined, washed with aqueous 10% sodium bisulfite solution (50 mL), water (50 mL) and brine (50 mL), dried over magnesium sulfate, filtered and concentrated in vacuo. Crystallization from 20% ethyl acetate/hexane gave the product (40 mg, 5%) as a white solid. The filtrate (0.5 g) was placed aside. ¹H NMR (300 MHz, d₆-DMSO) δ 1.64 (s, 6H), 6.98 (d, 1H, J=8.2 Hz), 7.19 (d, 1H, J=1.4 Hz), 7.57 (s, 1H), 7.62 (dd, 1H, J=1.4, 8.3 Hz), 10.43 (s, 1H), 12.91 (s, 1H). MS (ESI) [M−H]⁻ m/z 344/346. Anal. calcd. for C₁₅H₁₂BrN₃O₂: C, 52.04; H, 3.49; N, 12.14. Found: C, 51.4; H, 3.57, N, 11.59.

All publications cited in this specification are incorporated herein by reference herein. While the invention has been described with reference to a particularly preferred embodiment, it will be appreciated that modifications can be made without departing from the spirit of the invention. Such modifications are intended to fall within the scope of the appended claims. 

1. A method of providing progestational therapy to a mammal having endometriosis or fibroids, wherein said method comprises administering a progestationally effective amount of a compound having the structure of formula 1:

wherein: T is S; R₁ and R₂ are each, independently, hydrogen or C₁ to C₆ alkyl; or R₁ and R₂ are taken together to form —CH₂(CH₂)_(n)CH₂; n=1-5; R₃ is hydrogen, R₄ is hydrogen, R₅ hydrogen, R₆ is hydrogen or C₁ to C₆ alkyl; R₇ is hydrogen or alkyl; or a pharmaceutically acceptable salt thereof, to said mammal.
 2. The method according to claim 1, wherein in formula 1: R₁ and R₂ are each, independently, hydrogen or CH₁ to CH₆ alkyl.
 3. The method according to claim 1, wherein said progestationally effective amount is 0.02 μg/kg to 750 μg/kg.
 4. The method according to claim 1, wherein said R₁ and R₂ are taken together to form —CH₂(CH₂)_(n)CH₂— and n is
 1. 5. The method according to claim 1, wherein said R₁ and R₂ are taken together to form —CH₂(CH₂)_(n)CH₂— and n is
 2. 6. The method according to claim 1, wherein R₁ and R₂ are CH₁ to CH₆alkyl. 